Permanent section margin concordance after Mohs micrographic surgery with immunohistochemistry for invasive melanoma and melanoma in situ: A retrospective dual-center analysis.

BACKGROUND

Mohs micrographic surgery (MMS) for melanoma practices vary among dermatologic surgeons. The implementation of immunohistochemical staining in MMS for melanoma mitigates challenges associated with slide interpretation; however, the reliability of melanoma antigen recognized by T cells 1 (MART-1), the preferred immunostain for melanoma, has yet to be compared with permanent section pathology.

OBJECTIVE

To assess concordance rates of MART-1 frozen sections and permanent section pathologic interpretation of melanoma treated with MMS.

METHODS

A dual-center retrospective analysis was conducted to collect concordance and demographic data. Chi-square tests were performed for group comparisons of categorical variables.

RESULTS

Of the 379 permanent sections sent, 367 were concordant with frozen section pathology for an overall concordance rate of 96.8%. Cases were stratified into indeterminately concordant and indisputably concordant. Twenty-two (6%) of cases were indeterminately concordant, whereas 345 (94.0%) of cases were indisputably concordant.

LIMITATIONS: The concordance rate is derived from a comparison of adjacent tissue margins, an inevitable consequence of utilizing 2 techniques.

CONCLUSION

To the author's knowledge, this study represents the largest investigation examining concordance rates of MART-1 frozen sections in Mohs for melanoma. High concordance disputes the ongoing need for additional permanent margins when using MART-1 in routine cases.